1. Field of the Invention
This invention is concerned with substituted diphenyl ethers and their use as herbicides.
2. Description of the prior art
It has been proposed to use as herbicides 2-methoxy-benzoic acids (U.S. Pat. No. 3,013,054) and 4-phenoxybenzoic acids (French Pat. No. 1,502,538) substituted phenoxybenzoic acids (U.S. Pat. Nos. 3,979,437 and 4,164,409) and certain 4-trifluoromethyl-4'-nitrodiphenyl ethers (U.S. Pat. Nos. 3,928,416, 4,046,798, and 4,063,929). It is the discovery of this invention, however, that certain 4-trifluoromethyl-3'-nitrogen-substituted-4'-substituted diphenyl ethers are very effective herbicides.